The invention relates to a furnace which is suitable for use in processing samples of material specimens in space. Particularly, the invention is directed to a furnace having a high thermal gradient which is impressed upon the material as it is processed in the furnace.
Experiments in the past have been conducted using a standard Bridgman-Stockbarger type apparatus, which basically provides for passing the experiment material from a heated zone to a cold zone relying primarily on radiation heat transfer and gas conduction to transmit thermal energy into and out of the experiment sample. Whereas radiation heat transfer is adequate in the hot zone of such systems, it is very inefficient at the cold end of the thermal gradient. Poor heat transfer in the cold end coupled with the normal temperature "rolloff", or axial heat loss from an unguarded main heater limits the maximum thermal gradients achievable by this method.
Prior Bridgman-Stockbarger directional solidification systems designed for space flight have been limited to thermal gradients of approximately 250.degree. C./cm with the hot temperatures at 1000.degree. C. and a sample diameter of a few millimeters. With the present invention, thermal gradients of up to approximately 500.degree. C./cm in samples of up to 12 millimeters can be achieved.
Accordingly, an important object of the present invention is to provide a directional solidification furnace which may be used in processing specimens of material in space and which has a high thermal gradient.
Another important object of the present invention is to provide a directional solidification furnace for use in space operations which has a gradient zone in which the thermal gradient impressed upon the specimen of material may be controlled.
Still another important object of the present invention is to provide a directional solidification furnace which is comprised of modular components which can be rearranged to tailor the furnace to carry out different experiments.
Still another important object of the present invention is to provide a directional solidification furnace in which the heating elements of the furnace are modular components and may be expeditiously replaced.
Still another important object of the present invention is to provide a directional solidification furnace which provides manipulation of the sample in space by way of processing the material and then stores the processed sample for return to ground.